Electrodes for electron gun units



Oct. 22, 1957 J. H. JOHNSON ELECTRODES FOR ELECTRON GUN UNITS Filed July 1, 1955 /4 FIG. 6'

INVENTO)? JAY H. JOHNSON BY ATTORNEY United States Patent Ofiice Patented Oct. 22, 1957 ELECTRODES non ELECTRON GUN UNITS Jay H. Johnson, Mineola, N. Y., assignor to Johnson and Hoffman Manufacturing Corporation, Mineola, N. Y., a corporation of New York Application July 1, 1955, Serial No. 519,375

11 Claims. (Cl. 31382) This invention relates to electron discharge devices or tubes and more particularly to electronic television tubes.

The usual form of television tube employs a beam which is focused on the picture screen deposited on one end of the tube. In order to attain high efliciency in the projection of this beam in the tube, it has been the practice in the past, to create a bending effect of the beam, to correct for distortion of the projection of the beam toward the screen. This has been attained, in one respect, by providing electrodes in the gun mount; such as the second grid and the anode, with angle ends which cooperate to produce an angular lens effect, to bend the beam toward the beam axis of the tube.

While such distortion correction in the beam is compensated by the lens eifect, above described, the beneficial cooperation of the specified electrodes may be counteracted by a defocusing action on the beam if these electrodes are improperly aligned in the gun unit. Then, the electron beam is not focused correctly and a halo etfect is produced in conjunction with the travel of the beam across the screen.

It has been attempted to reduce misalignment of the electrodes in the gun unit by providing pilot holes or index perforations in the cooperating first and second grids, so that the angle end of the second grid could be readily mounted in proper orientation when the stack of electrodes in the gun structure is fabricated to the side posts of the mount. However, the close critical spacing between these grid electrodes introduced another conflicting condition, due to the difficulty of producing such pilot holes without burrs. It seems, that the infinitesimal fine metal burrs projecting into the short gap between the electrodes changed the control operating characteristics of the tube, by varying the cut-off point and thereby affecting the uniformity of the tube in operation.

An object of this invention is, to facilitate the assembly of the electrodes in the gun structure in television and similar tubes.

Another object of the invention is, to produce exact alignment of the electrodes in the fabrication thereof in the gun unit.

A further object of the invention is, to eliminate discordant effects in the operation of television tubes.

- Still another object of the invention is, to achieve high efliciency in the propulsion of the electron beam toward the picture screen of the tube.

These objects are attained, in accordance with this invention, by providing a plurality of parallel internal indentations or corrugations in the plane surface of the second grid electrode of the gun structure. These corrugations are located in parallel relation to the transverse axis extending across the center of the electrode through the low and high dimensions of the grid. The corrugations, preferably, are positioned as far as possible from thecenter of the electrode, to avoid distortion of the beam defining aperture in the control grid electrode. The indentations then serve as an index or pilot for positioning the electrode for attaching pins or straps thereto, whereby the electrode is supported in the mount assembly. Due to the deformation instead of the piercing of the electrode, no disfiguring burr formation is possible, to alter the control characteristics of the tube.

A feature of the invention relates to the formation of the indentations either complete or incomplete across the expanse of the electrode surface. In one embodiment, the parallel indentations are terminated before they reach the side wall or cylindrical surface of the electrode. This form may be desired to avoid distortion of the cup, due to the embossment of the fiat surface which might tend to produce out-of-round deformation of the cylindrical wall of the cup. In this instance, the index could be utilized as a primary locator for welding the pins to the electrode. On the other hand, when the indentations extend to the edge of the electrode these indices may act as registering or aligning means in the mounting of the electrodes in the unit.

These and other features and advantages of the invention may be realized more fully by reference to the following detailed description when considered in connection with the accompanying drawing, in which:

Fig. l is a view in elevation, partly in cross-section, showing the neck portion of a typical television tube with the gun mount supported therein;

Fig. 2 is a side elevation view of the array or stack of electrodes in the gun mount, taken on the line 2-2 of Fig. 1;

Fig. 3 is a bottom plan view of a grid electrode embodying one form of the invention;

Fig. 4 is a side view, in cross-section, of the grid electrode, taken on the line 44 of Fig. 3, and showing one of the corrugations extending across the electrode surface;

Fig. 5 is another cross-sectional view of the electrode of Fig. 3 taken on the line 55 of Fig. 4, to illustrate the configuration of the surface of the electrode;

Fig. 6 is a view, in elevation, and partly in cross-section, of the two grids, together with an alignment spacer between them;

Fig. 7 is a plan view of a grid electrode showing a modified form of the invention, and;

Pig. 8 is a view, in cross-section, of the electrode of Fig. 7, taken on the line 88, showing a different form of recess in the surface of the electrode.

Referring to the drawing, and particularly to Fig. 1, the invention is embodied in a television tube having a long tubular neck portion 10, provided with a stem 11, which supports a gun mount for projecting a beam of electrons along the axis of the tube toward a picture screen, not shown, on the opposite end of the tube. The gun mount comprises a plurality of cylindrical or surrounding electrodes arranged in series relation and primarily concerned with projecting a beam of electrons toward the screen. The gun mount involves an inverted cup electrode or first grid 12, having a central aperture 13, in the closed end; another cup electrode or second grid 14, and an elongated tubular anode 1 5. Mounted within the first grid is a small tubular cathode, not shown, which serves as the electron source for projecting an elec tronic beam through the array of electrodes constituting the gun mount.

The grid 12, is supported, in one form, by means of short Wires or studs 16, which extend radially in pairs from opposite 'sides of the cup. The grid 14 is also provided with similar pairs of studs 17, while the anode 15 has the studs 18, more widely spaced, to accommodate the longer length of this electrode. These studs are usually butt-welded to the surface of the electrodes, to radially project therefrom and the free ends are supporting. the various. electrodes, it should be understood, that other types of supports, such asstraps or other forms of connectors: may .be employed as the.

mounting means for the electrodes.

It will be noted, in the specific type of gun' mount to which this invention is particularly applicable, that"the second grid 14 and the anode 15 have complementary adjacent ends which define acute angles with respect to the cylindrical form of the body of these electrodes. These angular ends, which may vary in the range between seven and twelve degrees, depending on the type of electron lens desired, produce a focussing effect on the beam, to shift or bend it toward the axis of the gun structure in its travel to the screen.

The particular grid shown, has an angle of ten degrees, commonly referred to as a slash angle, to represent the relation of the open'end of the cup with respect to the closed end, or alternatively; to signify the height of the cylindrical wall on opposite sides of the cup. The anode has a similar angular end, to cooperate with the second grid, while the other end may be terminated in a uniform end wall, or, as shown, provided with a (3) three degrees slash angle.

The closed end of the grid 14 is provided with a central aperture 20, which in combination with the aperture 13 in the grid 12, constitute the beam forming and control means for acting on, the electrons projected from the source within the control grid '12." The open end of the grid 14 is shown with the angular edge curled or formed with a toroidal head, 21, to counteract coronaeffect adjacent the higher potential anode, although such curling may be eliminated if the potential difference is not too great or the space relationship between these electrodes is increased. The operating voltages applied to the electrodes, such as the grids 12 and 14, are supplied thereto by conductors 22 and 23, respectively, extending from the stem 11.

In view of the critical relationship of the slash angle ends-of thesecond grid 14 and the anode 15, to produce the electronic lensefiect for bending the beam toward the axial center of the tube, it is essential to insurethe accurate alignment and symmetrical location of these electrodes in the fabrication of the gun unit. In accordance with this invention, the coaxial alignment and symmetrical orientation of these electrodes are assured by providing parallel registration indentations, ridges or corrugations 24, as shown in Figs. 3 to 5 inclusive, to

function as self-biasing locating means for positioning the slash angle grid with respect to the axial planes of the gun unit.

The corrugations 24, preferably are formed to extend internally within the cup 14 and are arranged in parallel relation on opposite sides of the transverse plane extending through the center of the cup at the lowest and highestpoints of the cylindrical wall of the cup; The corrugations are formed with a radius of approximately .020 inch and extend across the surface of the cup, to form chordal ridges in collateral relation andbisecting a diametr-al plane on the surface of the electrode. As

shown in Fig. 5, the elongated indentations form semi! circular channels uniformly spaced on opposite "sides of the central zone of the cup and presenting open passageways across the whole surface of the closed end of the cup.

The function of the parallel indentations in orienting the grid 14 in the gun assembly is clearly shown in Fig. 6. In the fabrication of the electrodes tothe side posts 19 of the gun mount, a spacer or jig fixture 25, is' inserted between the two grids 12 and 1.4. This spacer 7 initially determines the exact space relationship between the grids so that the critical control characteristics of the tube may be attained. The spacer 25' is also provided with a pair of nodular cooperating beads or ribs 26, which correspond to the indentations 24 in the grid surface and thereby maintain the grid in proper relation until the side studs are fused in the posts 19. After this operation is completed the spacer 25 may be removed by merely sliding the spacer outwardly by means of the pull tab 27.

The complete transverse indentations in the surface of the grid 14 provide positive locating means, to orientthe electrodes in the gun mount and accomplish this functional step without introducing any complications in the close critical gap between the electrodes. This occurs because the embossing action in forming the ridges or corrugations eliminates any perforation of the metal and thereby avoids the introduction of burrs which are diflicult to remove in the metal surface. Accordingly, the

proposed arrangement definitely achieves the desired re sults without interference from objectionable imperfectionsin the surface of the electrode. 7

While the above. described arrangement forms one aspect of the invention, it .is possible to arrive at the same result by another method of fabrication. As shown in Figs. 7 and 8, the electrode 14 may be provided withshort parallel indentations or ridges 28, positioned in the same relation as shown in Figs. B and 4, but terminated at opposite ends before they extend to the circumferential edge of the cup electrode. The shortened ridges 28 maybe provided to reduce the tendency of the cylindrical wall to bend or be distorted when the corrugations are formed in the flatsurface if the wall thickness is I relatively low. a a a V a In this modified form of the invention, the short ridges .28 may be utilized as locating pilots, by seating the cup 14 with the short ridges on a suitable mating jig, not shown, the jig being adapted to be accurately oriented in a welding apparatus, or fixture. Then the studs 17 may be readily'welded in proper relation sothat the slash angle of the grid 14 will be truly aligned in the gun structure. A plain flat spacer, or one withoutprojections, is the only gap determinant when the electrodes are fused to the posts. The spacer is easily removed when the fusing operation is completed.

It is obvious that the deformation of the surface of the grid electrode with the acute angle 'end, in accordance with this invention, materially aids in the correct orientation of the grids in thegun mount, and, also eliminates variations in the operation ofthe device by avoiding the puncture of the metal so that burrs cannot be formed. The corrugations also increase the rigidityof the plane surface of the. grid electrode, whereby variations in the, space relation of the second grid is avoided, due. to high temperature expansion and contraction during. the operation of the device. p a e While this invention has been set forth specifically in several embodiments, it is, of course, understood, that various modifications may be made in the detailed structure of the electrodes, without departing fronrthe scope of the invention, as defined in the appended claims.

2. A metallic electrode, comprising a cup-shaped grid having an open end forming an acute angle, and means for'orient ing said angle end in accurate alignment with other electrodes along a common axis, said rneans beinga plurality of equally spaced recesses formed in the closed end of said electrode and extending in parallel relation to said a central plane through the low and high sides of cup-shaped grid.

3. A metallic electrode, comprising a cup-shaped grid having an open end forming an acute angle, and means for orienting said angle end in accurate alignment with i other electrodes along a common axis, said means being a pair of parallel elongated indentations formed in the closed end of said grid and extending toward opposite sides of the circumferential wall of said grid.

4. A metallic electrode, comprising a cup-shaped grid having an open end forming an acute angle, and means for orienting said angle end in accurate alignment with other electrodes along a common axis, said means being a pair of parallel short elongated corrugations formed internally in the fiat surface of said grid.

5. A metallic electrode, comprising a cup-shaped grid having an open end forming an acute angle, and means for orienting said angle end in accurate alignment with other electrodes along a common axis, said means being a pair of parallel short elongated corrugations formed internally in the fiat surface end of said grid, said corrugations terminating within the boundary of said flat surface and being equally spaced on opposite sides of the central axis in the same direction as the plane extending through the low and high points of the cylindrical wall of the electrode.

6. in an electron gun mount assembly, a plurality of electrodes including a cooperating cup grid and a cylindrical anode having complementary acute angle ends in close spaced relation, means extending from opposite sides of said electrodes for supporting them in aligned relation, support posts engaging said means to constitute a gun mount, said cup grid having a pair of internal elongated corrugations in parallel relation across the closed end thereof and coextensive with a plane passing through the low and high sides of the wall of said cup, and a removable spacer adapted to engage said corrugations to align said cup in accurate registry in said gun mount.

7. in an electron gun mount assembly, a plurality of electrodes including a cooperating cup grid and a cylindrical anode having complementary acute angle ends in close spaced relation, a pair of side support posts, radial connectors extending between the gun mount electrodes and said side posts, said cup grid having a closed end surface provided with a pair of corrugations extending across said surface in equal relation on opposite sides of a central plane projecting through the low and high sides of the cylindrical wall of said grid, said grid being adapted to be oriented in said gun mount by a removable aligning spacer, to engage said corrugations until said grid is affixed to said posts.

8. In an electron gun mount assembly, a plurality of.

electrodes including a cup grid and a cylindrical anode having complementary slash angle ends in close spaced relation, a pair of side support posts, radial connectors extending between the gun mount electrodes and said posts, said cup grid having a closed end surface provided with a pair of internal short nodular indentations extend ing in parallel relation on opposite sides of the center and collateral therewith on a line passing through the low and high sides of the cylindrical wall of said grid, said indentations serving as index location means in orienting said grid in accurate alignment in the assembly of the gun mount by a suitable spacer jig adapted to engage said grid during the fabrication of said grid to said support posts.

9. In an electron gun mount assembly, a plurality of electrodes including a cup grid and a cylindrical anode having complementary slash angle ends in close spaced relation, a pair of side support posts, radial connectors extending between the gun mount electrodes and said posts, said cup grid having a closed end surface provided with a pair of internal elongated recesses in parallel relation on opposite sides of the center and collateral therewith on a line passing through the low and high sides of the cylindrical wall of said grid, the method of indexing said grid in true orientation to the perpendicular planes of the axis, so that the lowest and highest points of the cylindrical wall of said grid are normal to the axis of the gun mount, which involves aligning said grid in relation to a fixture having embossments to register with said indentations, indexing said fixture to weld wire studs to the side walls at opposite points, whereby said grid may be accurately mounted in said gun mount.

10. In combination, in an electron gun mount, a plurality of electrodes including a cup grid having an apertured closed end and a curled open end with a slash angle, wire studs welded to the grid surface between said ends and positioned in perpendicular relation and at right angles with respect to a pair of elongated parallel recesses formed in the closed end in the grid surface, and a pair of side posts supporting said electrodes by engaging said wire studs to align said electrodes in the gun mount, said recesses serving as the indexing means in combination with a spacer to accurately align said grid in said gun assembly.

11. A metallic electrode, comprising a cup-shaped grid having an open end formed with an acute angle, and means for orienting said angle end in accurate alignment with other electrodes along a common axis, said means bein a pair of integral spaced recesses formed in the closed end of said electrode and projecting internally in relation to a central plane through the low and high sides of said cup-shaped grid.

Reterences fitted in the tile of this patent UNITED STATES PATENTS 

